[KC8QVO]

Yeah, youre probably right. As long as it flies then I am content for now, so lets hope for the best Ill look into getting a bigger engine for it, but in the mean time it wont hurt to give this a whirl. I dont care if it has barely enough power to keep it in the air (Ill have a handfull with the sticks trying not to nose up too high). I have tomorrow and 4 days next week to finnish it.

I am going to leave the wing at 120". If it doesnt fly right now, Ill put a bigger engine on it when I find one (hopefully a 18-20" bar chainsaw, about 50cc).

Steve

[hillmanr2]

You seem to convert allot of engines. What does this usually cost for a 50cc? For my type flying I will stick with aircraft engines like DA, BME,3w ect when I can finally afford one but I am curious.

[KC8QVO]

Well, at the rate I have been going I have paid a total of 0.00$ for 2 engines One is a 25cc (the one I am using) and the other is an 18cc (too small for an airplane, terrible power/weight ratio so Ill put it in a boat).

Just look around, you would be surprised what people throw out, or hand to you.

The 25cc is out of a leaf blower, it was sitting in the garage for several years with rotted out fuel lines. I took the engine out and cleaned it up a bit, put new lines on it, rigged a prop to it, and gave it some gas. The thing fired right up and has been running like new ever since.

The 18cc engine is from a weedwacker. My neighbor saw me working on my other engine and he came over saying he found the wacker on the road somewhere. He and his son were going to make something out of it but he didnt have the time or the know-how to get it to run. So I got that for free too

I was going to tear into my dads old chainsaw because it didnt work. Has a nice 3.4 cubic inch engine on it (roughly 50cc). However, when I started working on it before I took it apart I got it to run like a charm and dad changed his mind about letting me have it It starts on one pull now. I think the plug just wasnt getting a good connection, either to the wire or the block.

If you want to buy one, you can get a reconditioned chainsaw for under $200, depending on the size. You have to be careful with 2 cycle stuff as companies may put different engines in the same unit. I have heard of chainsaws having about 3 different engines for the same saw.

If you can, find a really powerful leaf blower. That is THE best way to get an engine. The blowers have longer engine shafts than the chainsaws and weedwackers. Most leaf blower engines even have some hardware on there you can rig to hold a prop rather than making a prop adapter. Mine, for example, had a washer on it that held the blower fan from turning on the shaft. I flipped it around and put 4 weld beads on it lined up so that the hub of my prop would sit right inside them. Once you tighten down on the nutt and the washer on the front it wont spin. However, during the dissasembly of the engine I damaged the shaft so the nutt eventually stripped out. Right now, once I get the airplane built and ready to test, Ill tighten the nutt down as far as I can get it and then tack weld it in place for some reassurence that it wont come off. Since the shaft is trash anyway it wont matter, I will just have to grind out the weld to get the prop off


A general rule of thumb for 2 cycle engines, especially the chainsaws, is to get the biggest engine you can find. The bigger the engine the better the power to weight ratio. The smaller engines (30cc and under) have terrible power to weight ratios. They also require much more cutting and trimming to get them to work in an RC airplane application.

Go to large engines, youll see my thread in there somewhere on my "leaf blower conversion engine".

I think youll find that converting engines like this saves you a LOT of $$ over a DA, 3W, ZDZ, Brisson, ect. 3W makes a 26cc engine and they want $600us for it. If you can find a 25-30cc 2 cycle engine off a weedwacker, chainsaw, or blower for free then you save yourself $600 Giant scale doesnt have to be expensive, you just have to know what to look for.

Steve